http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Kevin McFall (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
-
Use of Linear Viscoelastic Theory to Predict Resilient Behavior of Unbound Granular Materials
김성희,Kevin McFall,권재현,양지동,정진훈 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.5
This paper presents a methodology to estimate the stress-strain relationship of an unbound aggregate base using linear viscoelastic theory. Current Mechanistic-Empirical (ME) pavement design procedure adopts the resilient modulus concept to explain the behavior of granular materials for flexible pavement design. The resilient modulus is a stress dependent material property of granular materials that is different from strength. Although California Bearing Ratio (CBR) test results (i.e., stress and strain) can be used to estimate the strength of a granular material, it is not possible to estimate the resilient modulus directly. Therefore, it is necessary to estimate stress along with strain changes. The convolution integral enables the stress to be estimated from the given strain changes only if the relaxation modulus is measured. Aggregate specimens prepared from two different sources in Georgia were subjected to the relaxation modulus test. From the test data, the time-dependent stress due to a known strain rate was computed as a convolution integral of the strain. The computed stress-strain relationship was compared with that from the resilient modulus (MR) test. The results indicate that the stress-strain relationships from the MR test and the convolution integral are similar with nearly the same slopes when horizontal stress is assumed to be approximately 45% of vertical stress. This observation supports the use of the proposed methodology by state highway agencies to validate the MR test results for quality control and quality assurance of aggregate base material selection for pavement design and construction.
-
-
Trajectory control of planar closed chain fully compliant mechanism
Martin Garcia,Kevin McFall,Ayse Tekes 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.4
This study presents the design, analysis, dynamical modeling and control of a planar, flexure based closed chain compliant mechanism. Mechanism is designed as a single piece and comprised of rigid-flexure links connected in series. Base links of the mechanism can be actuated through two servo motors and translated along the horizontal direction using two step motors. Two servo motors are mounted on a rail-cart system and carts are equipped with belt drive to enable horizontal displacement. Dynamical model of the mechanism is derived by adapting pseudo rigid body modeling method, vector closure loop equations, Euler’s laws of motion and geometric constraints. Mechanism is 3D printed using thermoplastic polyurethane filament (TPU), motion of the mechanism is video recorded and position of the tip along with the motion of center of each links are captured using image processing. Mathematical model is simulated in Matlab Simulink and validated with the experimental data. A reference trajectory drawn within the workspace of the mechanism on iPad is successfully traced in real time using the simplified model, mirror imaging program and inverse kinematics. The proposed mechanism can be utilized as a haptic device and a compliant manipulator in industrial applications where high precision and larger workspace is desired.
-
Design, modelling and experimentation of a novel compliant translational dwell mechanism
Ayse Tekes,Hongkuan Lin,Kevin McFall 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7
A partially compliant novel translational double dwell mechanism is presented in this article. The designed mechanism consists of initially straight and preloaded pinned-pinned compliant links, rigid crank, slider-rail system and a DC motor. Slider doesn’t move until the critical buckling load is achieved and then snaps to its maximum and returns back to initial position as the crank completes a full rotation. Motion behavior of elastic members depending on the geometry and loading are investigated using Elastica theory. Kinematic analysis and dynamical model are obtained by representing the compliant pinned-pinned members as translational springs using polynomial formulation method. Mechanism behavior is also analyzed in Adams FlexView. Mechanism is built by 3D printing the flexible parts using polylactic acid (PLA). Displacement of the slider along with the deformation of buckling beams are recorded and deflection shapes are detected by machine vision measurement while the crank is subjected to complete rotation. Slider position is also recorded by a laser displacement sensor. Dynamical model results are validated by the experimental setup, machine vision measurement and Adams simulations.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
